During the extraction of hydrocarbons (or production of hydrocarbons), more particularly during the extraction of crude oil and the extraction of gas from subsurface strata, water, gas and hydrocarbons are always produced simultaneously and are raised toward the surface. The presence of water, in relatively large amounts, is thus inherent in the production of hydrocarbons and is the cause of many problems which will disrupt the production lines.
This is because the water present with the hydrocarbons extracted is often responsible for the corrosion of the pipes, ducts, tubes, valves and other metal components. This water can optionally be reinjected into the subsurface strata in order to help in the extraction of hydrocarbons. In addition, the water generally comprises dissolved or undissolved minerals which can precipitate and/or agglomerate, according to the temperature, pressure and pH conditions.
In order to solve these problems, it is well known to use several chemical additives which are injected into the mixtures of hydrocarbons, gas and water when they are extracted and/or into the subsurface strata where they are present, before their extraction.
These additives can be grouped together as corrosion inhibitors (or anticorrosion additives), bactericides, mineral scale inhibitors, hydrate inhibitors, demulsifiers, asphaltene inhibitors, paraffin inhibitors and others. These products are generally incompatible with one another and it is today necessary to inject them one by one, separately, which multiplies the operations and the storage, circulation and injection systems.
D. Ann Davis (“Development of combined multifunctional chemical inhibitors”, 2nd International Conference on “Controlling Hydrates, Waxes And Asphaltenes”, October 20th-21st, (1997), Aberdeen, IBC UK Conferences Ltd.) presented various possible asphaltene inhibitors/paraffin inhibitors/mineral scale inhibitors, hydrate inhibitors/corrosion inhibitors/paraffin inhibitors and also mineral scale inhibitors/paraffin inhibitors combinations.
The formulas combining mineral scale inhibitors, which are used to prevent the formation of deposits of mineral salts, such as, for example and without implied limitation, alkali metal and alkaline earth metal salts, such as calcium, barium or strontium salts and in particular calcium carbonate and/or calcium or barium sulfates, are not, however, mentioned in this publication. Likewise, this publication does not mention corrosion inhibitors.
In point of fact, it will be highly advantageous to be able to have available such a bifunctional additive simultaneously combining the properties of a corrosion inhibitor and the properties of a mineral scale inhibitor. Such a bifunctional additive would make it possible to reduce in particular the number of operations and also the number of injection lines and points, which would represent a considerable saving in the system for the extraction of the hydrocarbons.
It has now been discovered, and this represents a first subject matter of the invention, that it is possible to render a corrosion inhibitor and a mineral scale inhibitor compatible, that is to say to obtain a homogeneous, clear and in particular stable solution of at least one corrosion inhibitor and of at least one mineral scale inhibitor, which can be effectively used during the extraction of hydrocarbons, crude oil and/or gas, either for the extraction proper or in order to be added to the reinjected fluids which comprise a majority of water extracted from the production wells, referred to as production water in the continuation of the present account.